The late blight in potato remains one of the most devastating diseases in
potato production and resistance is a top priority in potato breeding.
Cisgenesis, which is the introduction of native genes from a crop's own gene
pool using GM technology thus retaining favorable characteristics, is a
promising new approach to resistance potato breeding.

Cisgenesis was utilized to introduce two late blight resistance genes,
Rpi-sto1 and Rpi-vnt1.1 from crossable species Solanum stoloniferum and
Solanum venturii, respectively, into three different potato varieties. The
first set of developed transgenics contained only one of the resistance
genes. These were used as references for resistance levels. Another set of
transgenics contained both of the resistance genes but without NPTII, the
kanamycin resistance marker. These two sets of transgenics were evaluated
via morphological evaluations, responsiveness to Avr genes and late blight
resistance. Eight cisgenic events from the second set showed broad spectrum
late blight resistance due to the activity of both resistance genes.

This marker-free transformation system is less genotype dependent and less
prone to vector backbone integration as compared to marker-assisted
transformation. Thereby, it provides an important tool for the successful
deployment of resistance genes in agriculture and contributes to the
production of potentially durable late blight resistant potatoes.

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